PREWITT: I'm a thirty-year man, in for the whole ride.
LORENE: I suppose it's different when a fellow makes a career out of it.
PREWITT: Nothing wrong with a soldier that isn't wrong with everyone else.
Prewitt wants to be a lifetime soldier, which further dashes Lorene's expectations of making a "proper" life with him. She wants to climb further up the social scale, while Prewitt doesn't mind being where he is.
LORENE: I enlisted too. Came out here on my own to get away from my hometown in Oregon.
PREWITT: How come?
LORENE: I had a boy friend. I was a waitress. He was from the richest family in town. He just married the girl suitable for his position. After three years of going around with me. It's a pretty story, isn't it? Maybe they could make a movie of it.
PREWITT: They did. Ten thousand of them.
Lorene was passed over for another girl because of her social status. This is probably a big motivating factor in her desire to live a "proper" life. She wants to remedy the problem that hurt her so much. Prewitt points out how common and tragically typical that sort of situation is.
PREWITT: Why's it funny if a guy wants to marry you?
ALMA: Because I'm a girl you met at the New Congress Club! And that's about two steps up from the pavement.
PREW: Okay—I'm a private no class dogface. The way most civilians look at it, that's two steps up from nothing.
Prewitt suggests that they both have the same amount of social status—which means they'd be good together. However, Alma doesn't see things that way, as demonstrated in the next quote.
ALMA: I—I won't marry you because I don't want to be the wife of a soldier.
PREWITT: Well, that… would be about the best I could ever do for you.
ALMA: Because nobody's going to stop me from my plan. Nobody, nothing. Because I want to be proper!
Alma wants to lead a pleasant, financially-secure, and successful life. It doesn't have much to do with love, which seems to be Prewitt's main motivation in pursuing his relationship with Alma even though he can't give her this "proper" life.
ALMA: In a year I'll have enough money saved. I'm going back to my hometown in Oregon. I'll build a house for mother and myself. Join the country club and take up golf. I'll meet the proper man with the proper position. I'll make a proper wife who can run a proper home, raise proper children. I'll be happy because when you're proper, you're safe.
Alma's main goal is safety, security. Now, she has to scrounge for her living as a "hostess" at the New Congress Club (in the book, she's a prostitute). Financial security is so important to her because it's one thing she's lacked her whole life—even her love for that other guy back in Oregon couldn't give her the security she desired. Plus, it'll help her take care of her mother too. So, it's a wholly practical and understandable plan, in a way, however much it might displease Prewitt.
KAREN: Once commissioned you go to the States.
WARDEN: An officer.
KAREN: Yes. Then I could divorce Dana and marry you.
WARDEN: An officer! I've always hated officers.
Warden doesn't like officers because (in part) they're in a class that's supposedly superior to him. He likes being a person with a lower rank who yet remains more competent than his supposed superiors.